Forward and reverse trailing shoe brake



Dec. 27, 1960 1... N. LAUER ETAL 8 FORWARD AND REVERSE TRAILING SHOE BRAKE Filed March 21, 1955 2 Sheets-Sheet 1 g Z/-- Z0 20 /9 I y A vy7' Dec. 27, 1960 L. N. LAUER ETAL FORWARD AND REVERSE TRAILING SHOE BRAKE 2 Sheets-Sheet 2 Filed March 21, 1955 V z m N M0 4 MM w/\ 8 I Z 3 i1 llli 4 I I n l I I I I I m J 5 5 A 7 Z a z United States Patent FORWARD AND REVERSE TRAILING SHOE BRAKE Leon Nicolas Lauer, Clichy, and Jean Pierre Ruet, Limeil- Brevannes, France, assignors to The Bendix Corporation, a corporation of Delaware Filed Mar. 21, 1955, Ser. No. 495,625

Claims priority, application France Mar. 27, 1954 4 Claims. (Cl. 18878) The invention relates to brakes and one of the objects thereof is to obtain the advantages of trailing shoe brake operation. The term trailing shoe designates shoes which, under the wrapping action exerted by the drum, tend to disengage from the latter.

An object of the invention is to provide a brake equipped with shoes operating as trailing shoes for both directions of vehicle movement and thus drum rotation.

Another object of the invention is to provide a brake in which there is automatic inversion of shoe ends which are actuated by the applying pressure when the direction of drum rotation is reversed.

Still another object of the invention is to provide a brake comprising two floating shoes in combination with two motor cylinders (i.e. fluid pressure responsive cylinders), each of said motor cylinders being provided with a pair of pistons.

Another object of the invention is to adapt the piston as anchors, the piston anchors being operative in accordance with the direction of drum rotation.

Another object of the invention is to provide suitable dampening of the respecttive pistons with the abutment flange secured to end of the motor cylinder.

Another object of the invention is to provide a balancing means for the weight of the brake shoes, which are relatively heavy intended for rail vehicles.

Other particulars and advantages of the invention will appear from the following description which refers to the accompanying drawings, in which:

Figure 1 is the plan view of a brake comprising two shoes operating as trailing shoes for the direction of IO- tation indicated by the arrow 1;

Figure 2 is a section of the fluid pressure responsive cylinder embodying the invention;

Figure 3 is a plan view, certain members being shown in section, of a brake embodying the invention; and

Figure 4 is a section along line 44 of Figure 3.

The brake shown in Figure 1 comprises two shoes 1 and 2 actuated at their ends 3 and 4 by means of fluid motors 5 and 6 having a single piston 7, acting through the intermediary of plungers 8 on the ends 3 and 4 designated as outlet ends for the direction of rotation of the drum, indicated by the arrow f. Shoes 1 and 2 are interconnected by return springs 9 and 10. With direction of rotation indicated by arrow corresponding to forward drive, the actuation of motor cylinders 5 and 6 transmits an applying pressure to the outlet ends 3, 4 of the shoes, while the opposite ends 11, 12 of said shoes take support on the closed end of the motor cylinders, so that the shoes operate as trailing shoes, solely in forward braking.

A brake having shoes operating as trailing shoes for both directions of rotation, is actuated by means of double acting motor cylinder 51 shown in Figure 2. These cylinders comprise two pistons 7' urged outwardly by means of springs 13. The springs 13 are compressed between sealing cups 14 on the faces of the respective. pistons, and a transverse internal flange 15 formed on the wall of the motor cylinder. The inlet port 16 of said cylinder is formed in this flange. Caps 17 which are secured to the ends of the motor cylinder, are provided with flanges 18 coaxial with the cylinder, and formed with apertures 19 through which extend plungers 20 connecting the pistons 7' to the adjacent shoe ends. Yielding washers 21 may be provided to dampen the impact of engagement of the respective piston with the flange 18-.

The brake shown in Figures 3 and 4 comprises two motor cylinders, similar to that shown in Figure 2, and

similar members thereof are indicated by the same reference numerals. means of bolts 21 to webs 22, 23 which form a part of a fixed support member 24, the medial plane of which registers with the medial plane of shoes 25, 26 cooperat ing with a rotating drum 27.

The shoes 25, '26 are floating shoes and can thus move relatively to the fixed support 24. The ends of said shoes may be connected to the respective pistons by means of plungers 20 the ends of which are spherically formedi extending into corresponding recesses formed on the re-- spective pistons on theone hand, and the ends of the: shoes, on the other hand. a

Motor cylinders 5 are connected together by means of a conduit 28 and the upper cylinder is provided with.

a bleeding port 29 closed by bleeder screw 30.

port 16 to cause in each motor cylinder a spreading of pistons 32, 33 in each motor cylinder thereby bringing: the shoes 25, 26 into contact with the drum 27. The: pistons 32 are shifted until they take support on abutment flanges 18 of caps 17 secured to the body of the cylinders where they act as anchors for the shoe ends, designated as entry ends for the direction of drum r0- tation indicated by the arrow The braking then takes place to a degree determined by the displacement of pistons 33, in accordance with the applying pressure transmitted to these pistons acting on the outlet ends of the shoes for the said direction of the drum rotation.

It can be easily noted that if the direction of the rotation shown by arrow f is reversed, pistons 33 will take support against abutment flanges 18 and the degree of braking will be determined by the pistons 32.

Yielding members similar to washers 21 of Figure 2 may be used to dampen the engagement of the respective piston with abutment flange 18.

On one of the webs 22, forming part of the fixed support member of the brake, there are provided two arms 34, and a third arm 35 is formed on web 23'. The Webs of the shoes project between said arms 34 on the one hand and arm 35 on the other hand, to laterally position the shoes. Screws 37 serve to laterally guide the shoes.

When the brake is applied to rail vehicles, the shoes 25, 26 which are relatively heavy, are provided with two balancing devices each comprising a cranked lever designated generally by reference numeral 38. Each of the balancing devices has an arm 39 with a fork end portion 40 which engages a pin 41 carried by the respective shoes. A second arm 42 of the lever is loaded by a. spring 43 located in a recess formed on the fixed support member 24, to balance completely or partially the weight of the shoes 25, 26.

We claim:

1. A brake comprising two floating shoes, two fluid Motor cylinders 5' are secured by amazes 3 pressureresponsive cylinders, each having a pair of pistons and each located between a pair of adjacent shoe ends, abutmentsprovided in each of the cylinders to limit 7 the outward movement of said pistons, :return springs loading the shoes, the pistons 'being normally disengaged from said abutments under the action of the return springs, one piston in each cylinder being adapted to take support in accordance'with the direction of drum rotation on a corresponding abutment, said abutment thereby acting as an anchorage means for the entry end of one shoe while the second piston of the said cylinder transmits an applying pressure'to the outlet end .of the second shoe so that both shoes are operated as trailing shoes,

the function of the 'pistons' being invested for the opposite direction of the drum rotation.

2. A brake' comprising azrotating drum, a pair of Show and a balancing device for compensation of the weight of the shoes, said device comprising a cranked .lever p'ivotallymounted on a fixed support and having two arms one of which is formed as a fork, and a merrrber carried by each of the shoes and adapted .to cooperate with said fork, the weight of said shoes being supportable by said balancing device acting through said member, the second arm being associated with a spring the reaction of which is transmitted to the fixed support.

3. A brake comprising 'a rotatable drum, two floating arcuate brake shoes arranged 'in end' to end relation and engageable with said drum, actuating means for exerting applying force simultaneously .at each end of each shoe and efiecting their en ag ment'wi-th said drum, said shoe ends being the "leading or trailing ends depending on the direction of rotation of said drum, and abutment means so positioned relative to said actuating means that upon movement of the brake shoes toward the actuating means at the trailing ends the actuating means at the leading ends of the shoes in either direction of drum rotation engage their respective abutment means when the actuating means at the leading ends of the shoes are fully actuated and the actuating means at the trailing ends of said shoes have suflicient remaining movement that the applying action on said shoes is'determined primarily at the trailing ends thereof in either direction of drum rotation.

4. A brake :as set forth in claim '3 in which the actuating means include a pair of cylinders and a pair of fluid pressure responsive pistons in each cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,718,526 Christensen June 25, 1929 1,758,671 Loughead et al. May 13, 1930 2,125,266 Begg 'et a1. Aug. 2, 1938 2,319,583 Chambers May 18, 1943 2,345,198 Goepfrich Mar. 28, 1944 2,356,517 Hale Aug. 22, 1944 2,587,832 Frick Mar. 4, 1952 2,833,378 'Main May 6, 1958 FOREIGN PATENTS 675,579 Great Britain July '16, 19,52 

